1. Field of the Invention
The present invention relates generally to adhesion between hydrophobic material layers formed upon hydrophilic material layers within fabrications such as but not limited to microelectronics fabrications. More particularly, the present invention relates to methods for promoting adhesion between hydrophobic material layers formed upon hydrophilic material layers within fabrications such as but not limited to microelectronics fabrications.
2. Description of the Related Art
Microelectronics fabrications are formed from microelectronics substrates over which are formed patterned microelectronics conductor layers which are separated by microelectronics dielectric layers.
In the process of forming microelectronics fabrications, it is common in the art of microelectronics fabrication to encounter microelectronics processing steps where it is required to adhere a hydrophobic material layer, such as but not limited to an organic polymer hydrophobic material layer such as a photoresist material layer, onto a hydrophilic material layer, such as but not limited to a hydrated oxide hydrophilic material layer. In general, within fabrications such as but not limited to microelectronics fabrications, hydrophobic material layers are intended as material layers having a sessile deionized water drop contact angle of greater than about 55 degrees with respect to the hydrophobic material layer surface while hydrophilic material layers are intended as material layers having a sessile deionized water drop contact angle of less than about 55 degrees with respect to the hydrophilic material layer surface.
Conventionally, it is common in the art of microelectronics fabrication to employ an organofunctional silane coupling agent material bearing both a hydrophobic group and a condensable hydrophilic group to form an organofunctional silane coupling agent material layer interposed between the hydrophobic material layer and the hydrophilic material layer in order to enhance adhesion between the hydrophobic material layer and the hydrophilic material layer. A particularly common organofunctional silane coupling agent material employed for forming such organofunctional silane coupling agent material layers within microelectronics fabrications is hexamethyldisilazane (HMDS).
While hexamethyldisilazane (HMDS) is commonly employed when forming organofunctional silane coupling agent material layers interposed between hydrophobic material layers and hydrophilic material layers within microelectronics fabrications, hexamethyldisilazane (HMDS) derived organofunctional silane coupling agent material layers are not entirely without problems when employed as adhesion promoter layers interposed between hydrophobic material layers and hydrophilic materials layers within microelectronics fabrications. In particular, it has been observed within microelectronics fabrications employing hexamethyldisilazane (HMDS) organofunctional silane coupling agent material layers interposed between positive deep ultraviolet (DUV) hydrophobic photoresist material layers and hydrated hydrophilic silicon containing material layers that the positive deep ultraviolet (DUV) hydrophobic photoresist material layers are often not uniformly developed after photoexposure. A series of schematic cross-sectional diagrams illustrating a microelectronics fabrication having formed therein such a non-uniformly developed positive deep ultraviolet (DUV) hydrophobic photoresist layer is illustrated in FIG. 1 to FIG. 4.
Shown in FIG. 1 is a substrate 10 employed within a microelectronics fabrication, where the substrate 10 has formed thereupon a hydrated hydrophilic silicon containing layer 11. As is illustrated within FIG. 1, the hydrated hydrophilic silicon containing layer 11 has pendent hydroxyl (--OH) groups covalently bonded thereupon which provide at least in part the hydrophilic character to the hydrated hydrophilic silicon containing layer 11. Shown also in FIG. 1 is a molecule of hexamethyldisilazane (HMDS) in the vicinity of the surface of the hydrated hydrophilic silicon containing layer 11.
Referring now to FIG. 2, there is shown a schematic cross-sectional diagram illustrating the results of further processing of the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 1. Shown in FIG. 2 is a schematic cross-sectional diagram of a microelectronics fabrication otherwise equivalent to the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 1, but wherein the hexamethyldisilazane (HMDS) molecule has reacted with the pendant covalently bonded hydroxyl (--OH) groups to for a covalently bonded trimethylsilyl derivatized hydrophobic silicon containing layer 11' and ammonia, or in the alternative some lower order alkyl amine derived from the hexamethyldisilazane (HMDS).
Referring now to FIG. 3, there is show a schematic cross-sectional diagram illustrating the results of further processing of the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 2. Shown in FIG. 3 is a schematic cross-sectional diagram of a microelectronics fabrication otherwise equivalent to the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 2, but wherein there is formed upon the trimethylsilyl derivatized hydrophobic silicon containing layer 11' a blanket positive deep ultraviolet (DUV) hydrophobic photoresist layer 12 which is photoexposed through a photoexposure reticle 13 while employing a deep ultraviolet (DUV) photoexposure radiation beam 14.
Referring now to FIG. 4, there is shown a schematic cross-sectional diagram illustrating the results of further processing of the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 3. Shown in FIG. 4 is a microelectronics fabrication otherwise equivalent to the microelectronics fabrication whose schematic cross-sectional diagram is illustrated in FIG. 3, but wherein the photoexposed blanket positive deep ultraviolet (DUV) hydrophobic photoresist layer 12 has been developed to form the partially patterned positive deep ultraviolet (DUV) hydrophobic photoresist layer 12'. As is illustrated within the schematic cross-sectional diagram of FIG. 4, the partially patterned positive deep ultraviolet (DUV) hydrophobic photoresist layer 12' is incompletely patterned with residue layers formed most closely adjoining the trimethylsilyl derivatized hydrophobic silicon containing layer 11', as well as "T" top protrusions defining the upper surfaces of apertures formed within the partially patterned deep ultraviolet (DUV) hydrophobic photoresist layer 12'.
Partially patterned photoresist layers, such as the partially patterned positive deep ultraviolet (DUV) hydrophobic photoresist layer 12' as illustrated within the schematic cross-sectional diagram of FIG. 4, are undesirable within microelectronics fabrication since they impede proper patterning of layers formed beneath those partially patterned photoresist layers.
Beyond the foregoing problem pertaining to difficulty in forming a fully patterned positive deep ultraviolet (DUV) hydrophobic photoresist layer upon a trimethylsilyl derivatized hydrophobic silicon containing layer while employing a hexamethyldisflazane (HMDS) organofunctional silane coupling agent material layer within a microelectronics fabrication, hexamethyldisilazane (HMDS) organofunctional silane coupling agent materials are generally also known as expensive materials in comparison with many other materials which are employed within microelectronics fabrication, thus contributing to added microelectronics fabrication cost. Finally, hexamethyldisilazane HMDS) organofunctional silane coupling agent materials are often also known as particularly toxic materials in comparison with many other materials which are employed in microelectronics fabrication. Such toxicity generally requires that hexamethyldisilazane (HMDS) organofunctional silane coupling agent materials require special handling when employed within microelectronics fabrication.
It is thus desirable within the art of microelectronics fabrication to provide methods and materials through which adhesion between hydrophobic material layers formed upon hydrophilic material layers within microelectronics fabrications may be enhanced without the use of hexamethyldisilazane (HMDS) organofunctional silane adhesion promoter material layers formed interposed between the hydrophobic material layers and the hydrophilic material layers. It is towards that goal the present invention is directed.
Various methods and materials have been disclosed in the art of microelectronics fabrication for fabricating photoresist layers and photoresist materials which may be employed within microelectronics fabrications.
For example, Durham, in U.S. Pat. No. 4,806,458 and U.S. Pat. No. 4,692,398, discloses a photoresist stripping composition, and a method for stripping a photoresist layer from a microelectronics substrate while employing the photoresist stripping composition, where the photoresist stripping composition employs a hexaalkyldisflazane, such as hexamethyldisilazane (HMDS), within a solvent composition comprising at least one of a propylene glycol alkyl ether and a propylene glycol alkyl ether acetate. The photoresist stripping composition when dried to a tack free state may also serve as an adhesion promoter layer for promoting adhesion of a photoresist material layer formed over the microelectronics substrate.
In addition, Davidson, in U.S. Pat. No. 5,618,655, discloses a method for reducing trace metal impurity levels within photoresist materials employed within microelectronics fabrications. The method employs an aqueous alkaline extraction of the trace metal impurities from the photoresist materials through use of an immiscible co-solvent mixture which may include as one of the solvent components propylene glycol methyl ether acetate.
Desirable in the art of microelectronics fabrication are methods and materials through which hydrophobic material layers, such as photoresist layers, may be formed upon hydrophilic material layers, such as hydrated oxide layers, within microelectronics fabrications, with enhanced adhesion without employing hexamethyldisilazane (HMDS) organofunctional silane adhesion promoter material layers interposed between the hydrophobic material layers and the hydrophilic material layers. It is towards that goal that the present invention is directed.